Carvalho Márcia, Hawksworth Gabrielle, Milhazes Nuno, Borges Fernanda, Monks Terrence J, Fernandes Eduarda, Carvalho Félix, Bastos Maria Lourdes
CEQUP, Toxicology Department, Faculty of Pharmacy, University of Porto, Rua Aníbal Cunha, 164, 4050-047 Porto, Portugal.
Arch Toxicol. 2002 Oct;76(10):581-8. doi: 10.1007/s00204-002-0381-3. Epub 2002 Aug 1.
The metabolism of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) has recently been implicated in the mechanisms underlying ecstasy-induced neurotoxicity and hepatotoxicity. However, its potential role in ecstasy-induced kidney toxicity has yet to be investigated. Thus, primary cultures of rat and human renal proximal tubular cells (PTCs) were used to investigate the cytotoxicity induced by MDMA and its metabolites methylenedioxyamphetamine (MDA), alpha-methyldopamine (alpha-MeDA), and the glutathione (GSH) conjugates 5-(glutathion- S-yl)-alpha-MeDA and 2,5- bis(glutathion- S-yl)-alpha-MeDA. Cell viability was evaluated using the mitochondrial MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. MDMA and MDA were not found to be toxic to either rat or human PTCs at any concentration tested (100-800 micro M). In contrast, 800 micro M alpha-MeDA caused 60% and 40% cell death in rat and human PTCs, respectively. Conjugation of alpha-MeDA with GSH resulted in the formation of even more potent nephrotoxicants. Thus, exposure of rat and human PTC monolayers to 400 micro M 5-(glutathion- S-yl)-alpha-MeDA caused approximately 80% and 70% cell death, respectively. 5-(Glutathion- S-yl)-alpha-MeDA (400 micro M) was more toxic than 2,5- bis(glutathion- S-yl)-alpha-MeDA to rat renal PTCs but equally potent in human renal PTCs. Pre-incubation of rat PTCs with either acivicin, an inhibitor of gamma-glutamyl transpeptidase (gamma-GT), or bestatin, an inhibitor of aminopeptidase M, resulted in increased toxicity of 5-(glutathion- S-yl)-alpha-MeDA but had no effect on 2,5- bis(glutathion- S-yl)-alpha-MeDA-mediated cytotoxicity. The present data provide evidence that metabolism is required for the expression of MDMA-induced renal toxicity in vitro. In addition, metabolism of 5-(glutathion- S-yl)-alpha-MeDA by gamma-GT and aminopeptidase M to the corresponding cystein- S-yl-glycine and/or cystein- S-yl conjugates is likely to be associated with detoxication of this compound. Thus, it appears that toxicity induced by thioether metabolites of ecstasy at the apical membrane of renal proximal tubular cells is the result of extracellular events, presumably redox cycling.
3,4-亚甲基二氧甲基苯丙胺（MDMA，摇头丸）的代谢最近被认为与摇头丸诱导的神经毒性和肝毒性的潜在机制有关。然而，其在摇头丸诱导的肾毒性中的潜在作用尚未得到研究。因此，使用大鼠和人肾近端小管细胞（PTCs）的原代培养物来研究MDMA及其代谢产物亚甲基二氧苯丙胺（MDA）、α-甲基多巴胺（α-MeDA）以及谷胱甘肽（GSH）缀合物5-（谷胱甘肽-S-基）-α-MeDA和2,5-双（谷胱甘肽-S-基）-α-MeDA诱导的细胞毒性。使用线粒体MTT [3-（4,5-二甲基噻唑-2-基）-2,5-二苯基四氮唑溴盐] 测定法评估细胞活力。在所测试的任何浓度（100 - 800 μM）下，未发现MDMA和MDA对大鼠或人PTCs有毒性。相比之下，800 μM的α-MeDA分别导致大鼠和人PTCs中60%和40%的细胞死亡。α-MeDA与GSH的缀合导致形成更强效的肾毒性物质。因此，将大鼠和人PTC单层暴露于400 μM的5-（谷胱甘肽-S-基）-α-MeDA分别导致约80%和70%的细胞死亡。5-（谷胱甘肽-S-基）-α-MeDA（400 μM）对大鼠肾PTCs的毒性比2,5-双（谷胱甘肽-S-基）-α-MeDA更大，但在人肾PTCs中效力相同。用γ-谷氨酰转肽酶（γ-GT）抑制剂阿西维辛或氨肽酶M抑制剂贝司他汀预孵育大鼠PTCs会导致5-（谷胱甘肽-S-基）-α-MeDA的毒性增加，但对2,5-双（谷胱甘肽-S-基）-α-MeDA介导的细胞毒性没有影响。目前的数据提供了证据表明在体外MDMA诱导的肾毒性的表达需要代谢。此外，γ-GT和氨肽酶M将5-（谷胱甘肽-S-基）-α-MeDA代谢为相应的半胱氨酸-S-基-甘氨酸和/或半胱氨酸-S-基缀合物可能与该化合物的解毒有关。因此，看来摇头丸的硫醚代谢产物在肾近端小管细胞顶端膜诱导的毒性是细胞外事件的结果，大概是氧化还原循环。
